1. Field of the Invention
This invention pertains to highly concentrated formulations of antibodies, which are particularly suitable for subcutaneous administration. The invention further provides stable, highly concentrated (e.g., ≧100 mg/ml protein) liquid formulations.
2. Description of the Related Art
There is a significant demand for highly concentrated liquid antibody formulations. However, highly concentrated protein formulations pose several problems. One problem is instability due to the formation of particulates. With reconstituted lyophilized preparations to generate liquid formulations, this problem has been addressed through the use of surfactants (e.g., a polysorbate), but surfactants are unsuitable for liquid formulations, because they render further processing difficult. Moreover, surfactants further do not reduce the increased viscosity caused as a result of numerous intermolecular interactions from the macromolecular nature of antibodies.
Although surfactants have been shown to significantly reduce the degree of particulate formation of proteins, they do not address the problem of increased viscosity that makes difficult the manipulation and administration of concentrated antibody formulations. Antibodies tend to form viscous solutions at high concentration because of their macromolecular nature and potential for intermolecular interactions. Moreover, pharmaceutically acceptable sugars are often used in large amounts as stabilizers. Such sugars can enhance the intermolecular interactions, thereby increasing the viscosity of the formulation. Highly viscous formulations are difficult to manufacture, draw into a syringe and inject subcutaneously. The use of force in manipulating the viscous formulations leads to excessive frothing, which can lead to denaturation and inactivation of active biologics. Satisfactory solution of this problem is lacking.
While the prior art indicates numerous example of excipients that can be suitably employed to create pharmaceutical formulations, very few proteins have been successfully formulated above 100 mg/ml, or have techniques for doing so been described.
Applicants have discovered that Arginine, specifically Arginine-HCl is particularly suited for highly concentrated liquid protein or antibody formulations.
Stable isotonic lyophilized protein formulations are disclosed in PCT publication WO 97/04801, published on Feb. 13, 1997, the entire disclosure of which is hereby expressly incorporated by reference. The disclosed lyophilized formulations can be reconstituted to generate high protein-concentration liquid formulations without apparent loss of stability. However, the potential issues associated with the high viscosity of the reconstituted formulations are not addressed. Protein aggregation has been reduced previously through the addition of sugars, but doing so can dramatically increase the viscosity and osmolarity, thereby rendering processing and use impractical.
Applicants co-pending application U.S. Ser. No. 09/971,511, filed Oct. 4, 2001 discloses high protein concentration, but low viscosity formulations achieved: 1) through low pH (about 4.0 to 5.3); 2) high pH (about 6.5 to 12.0), or 3) increasing the total ionic strength of the formulation by the addition of salts or buffers. However, while increased ionic strength does decrease the viscosity of the formulation (such as with NaCl), it may also result in increased turbidity of the solution, which is often associated with the formation of protein particles (e.g., aggregation). Thus an optimal high concentration protein formulation must overcome challenges of stability, viscosity, osmolarity and turbidity.